We have tested the use of atomic oxygen to prepare 3d oxide-metal interfaces for which standard reactivedeposition techniques based on molecular oxygen fail in providing well-defined chemical composition andcontrolled atomic structure and morphology. Using monolayer NiO001 on Ag001 as a model system, wefind that NiO001/Ag001 films grown by atomic oxygen have a two-dimensional highly stoichiometric11 structure and a uniform monoatomic thickness, while those grown by conventional O2 have a nonstoichiometric21 structure or a three-dimensional morphology. Atomic oxygen may provide a practical wayto prepare 3d oxide-metal interfaces with highly controlled stoichiometry, structure, and morphology.